The goal of this project is to promote selective adsorption of proteins to modified surfaces. Several scenarios are proposed and are being investigated simultaneously but all involve self-assembly of molecules with thiol-terminated ligands on atomically-flat gold surfaces. Reactions are then carried out on this derivatized monolayer in order to hierarchically build two-dimensional arrays of active receptors which selectively adsorb a specific protein and thus elicit specific cell responses. Current activity is focused on a series of porphyrins, which possess an ideal size for recognition group spacing.